1. Field of the Invention
The present invention relates to see-through lenses. More particularly, the present invention is directed to uniquely constructed, toric-shaped lenses adaptable primarily for use in non-prescription sunglasses, sport goggles and the like.
2. Description of the Related Art
As well as enhancing vision, eyeglasses also serve to protect the eye against all types of foreign objects. Initially, the lenses employed in such eyeglasses were routinely made of glass and were substantially flat in shape, a condition which created significant distortion around the periphery of the lenses. More recently, lenses have been made of a variety of plastic or plastic-like materials, often having dramatically curved surfaces. For example, swim or riding goggles are well know to have teardrop-shaped lenses. While such lenses may reduce aerodynamic drag, a wearer may suffer from undesirable peripheral distortion when viewing through such lenses.
Curved lenses employed in sports goggles, sun glasses or the like may be more or less elliptical in shape as required by the specific application. Such applications may include fashion eye wear, performance eye wear including swim and sport goggles, and sunglasses, as well as all manner of protective eye wear for use at home and on the job. In any particular use, the arc of the curved lens may vary in shape dependent on the overall circumference of the curved lens necessary to achieve undistorted vision. Lenses may be employed with a slight spherical appearance, i.e., a modified toric or ovoid arc. In such slightly curved lenses, there is a variable radius of curvature somewhere between 8-12 mm, e.g., a 12 base curve. In effect, the distance between the lens and eye may well differ at different locations on the lens. This may create significant distortion at the periphery of each lens.
The Government of the United States has procured a protective facemask assembly having a pair of semi-curved lenses of toric or ovoid configuration. While these lenses may seem superficially similar to the present invention, closer inspection reveals a number of significant differences. Because the Government lenses are mounted in pockets creating the nose bridge of the facemask, the edge of each Government lens is truncated or cut-off to allow for assembly into its respective pocket. This naturally creates peripheral distortion for the wearer of the mask, when attempting to view through the truncated portion located near the mask nose. Another drawback of the Government procured toric lens is the use of only a single size lens, i.e.; xe2x80x9cone size fits all.xe2x80x9d Each Government lens also incorporates two parts, a toric lens and surrounding flange joined by a dedicated and detectable seam. This seam itself can distort the vision of the wearer. Furthermore, there is no suggestion that the flange surrounding the Government""s toric lens can be made of any desirable configuration.
It is clear that there exists a need in the art for an improved viewing lens capable of providing distortion free viewing in a fashionable design equally adaptable for use in most all types of eyewear including conventional, non prescription sunglasses. As will become apparent, the present invention provides a uniquely configured bugeyes(copyright) lens assembly which optimizes peripheral vision while minimizing the size of each lens and thus maximizing the aerodynamic flow of air around the lens.
There is a need in the art for eyewear lenses capable of providing maximum field-of-view with a minimum of distortion. Such lenses need be adaptable for eyewear including sports wear and fashion wear. The present invention provides such unique toric-shaped lenses and associated eyewear.
The present invention is directed to a unique, toric-shaped lens adaptable for use as a viewing lens in protective eyewear, sunglasses, sport goggles and swim wear utilized above the water. The invention includes a unique Bugeyes(copyright) lens wherein the radius of curvature of the lens is substantially constant from a normal eyeball as it scans throughout the viewing field. Because the radius of curvature is substantially constant, the toric-shaped, Bugeyes(copyright) lens provides for continuous, undistorted peripheral vision. The radius of curvature of the lens is greater than 15 mm and preferably in the range of 19-23 mm, e.g., an exemplary lens with a base curve in the range of 19-23.
The Bugeyes(copyright) lens is of substantially constant thickness throughout the field of view and the lens is optically correct and free from any prism effect throughout the periphery of the lens. The lens has a 0 power of magnification at all points in the viewing field when constructed of material having an index of refraction of between 1.57 and 1.60. A further feature of the present invention is that the closer the lens is positioned relative to the eye, the smaller in size the lens needs be. The lens should be no smaller than necessary to provide freedom of movement of the wearer""s eyelashes. As the separation between the lens and the eye increases, the size of the lens will also increase, with the maximum practical size of the lens directly related to the facial geometry and to the point at which the wearer""s eyes field of vision overlap.
A pair of toric-shaped lenses according to the present invention may be directly attached to a pair of stems (also referred to as temples) extending about opposite sides of the wearer""s head or attached to a goggle strap of any size and shape. Each toric-shaped lens may include a flange portion partially or totally surrounding the viewing lens. At the point where the lens and flange intersect, a seam may exist which visually differentiates between the lens and the flange. In one embodiment of the present invention, the lens and surrounding flange are separately constructed and joined at the seam. Alternatively, the lens and flange may be integrally constructed out of the same material with a gradual transition between the lens and flange portions providing a seamless appearance. Regardless of the type of construction employed, these flanges may serve to secure the lenses to a pair of eyeglass stems, padding, nose piece, ear piece, strap or the flange may be purely ornamental. The flange can be of any size, shape, color, texture or material. It is also within the scope of the present invention to dispense with the flange altogether by directly connecting each toric-shaped lens to the goggle or glass frame.
The percentage of the toric lens which must be used for the field-of-view should be sufficient to provide undistorted peripheral vision of at least 20xc2x0 vertical and 20xc2x0 horizontal and may be as great as 80xc2x0 to 94xc2x0 at the distal portion of each lens. As the proximal portion of the toric lens, the nose would restrict overall monocular vision to field-of-view of about 140xc2x0 to 156xc2x0.